Through concurrent behavioral and cortical electrophysiological measures, the proposed research seeks to elucidate basic incremental and decremental learning processes involved in what traditionally were regarded as Pavlovian conditioning control treatments. Recent classical reward conditioning studies demonstrate that US-Alone and CS/US Unpaired treatments involve incremental and decremental learning to background cues, which is not reflected directly in behavior, but which must be inferred on the basis of "pseudoconditioned" responses to novel or unpaired CSs. Other reward conditioning studies demonstrate that US-Alone presentations at regular intervals are sufficient to produce acquisition of cyclical cortical steady ("DC") potentials consisting of prereinforcement ("excitatory") shifts in one polarity followed by postreinforcement ("inhibitory") shifts of opposite polarity whose durations are controlled by the interreinforcement interval. These acquired potentials appear to provide distinctive information about conditioning processes which has not been detected in mass unit activity measures derived through the same hybrid electrodes, nor in concurrent behavior measures. Both "pseudoconditioning" and steady potential phenomena have been interpreted as reflecting "expectancies" of reinforcement ("excitatory" associations) and nonreinforcement ("inhibitory" associations) conditioned to contextual background (apparatus, temporal, trace, and sequential aftereffect) cues on the basis of their contiguity with reinforcement and nonreinforcement, respectively. The proposed classical reward conditioning studies attempt to assess what distinctive information is provided by cortical steady potentials, mass unit activity, and behavioral URs, "pseudo CRs," and CRs, and to assess the relationships between them. Such studies appear essential to the search for classical conditioning mechanisms postulated to underlie many kinds of animal learning and performance.